RTL1 and multiple congenital anomalies due to 14q32.2 maternally expressed gene defect: Here, we demonstrate that Rtl1 also plays an important role in fetal/neonatal skeletal muscle development: its deletion and overproduction in mice lead to neonatal lethality associated with severe but distinct skeletal muscle defects, similar to those of Temple and Kagami-Ogata syndromes, respectively.